The disclosure this week that former IRS supervisor Lois Lerner used a private email account for agency business proves that "the cover-up continues" between the agency and the Justice Department, Judicial Watch President Tom Fitton told Newsmax TV on Friday.

"The Justice Department is conflicted, is compromised," Fitton told "Newsmax Prime" hosts J.D. Hayworth and Miranda Khan. Judicial Watch has sued the IRS over the agency's targeting of conservative groups.

"It wasn't just about denying or stalling exemption applications or audits. They were talking about putting people in jail. Now, we expect the Justice Department and the FBI to investigate their own involvement in this scandal.

"I don't understand how that's going to work — and if we had a competent system, we would have an independent council, or at least a special counsel, investigating this," Fitton said.

The Justice Department told the federal judge hearing Judicial Watch's lawsuit that Lerner had a personal email account under an assumed name that she used for agency business. The IRS' official database also contained documents from Lerner's home computer, the department said.

"There was a letter from Congress last year in April, where they alerted the IRS, or referenced this account, in a letter asking for a criminal investigation," Fitton told Hayworth and Khan.

"So, the Justice Department knew about it. The IRS knew about it — but they waited a long time, two years really after the scandal was uncovered, to alert the court in our Freedom of Information Act case about this new source of potential information."

Lerner, who retired from the IRS in 2013 in the wake of the scandal, could face criminal charges if any of the agency's information were on her personal system, Fitton said.

"If she was just using it for government business, it may be a government account," Fitton said. "If there was IRS confidential information on it — essentially confidential taxpayer information is very much protected by law — and if you violate and let it get out or leave it in unsecured locations, you can be subject to criminal prosecution.

"If there was confidential IRS data on this system or on this email account, she could be in criminal trouble."

He also suggested that Congress impeach IRS Commissioner John Koskinen.

"The commissioner of the IRS knew for months that the Lois Lerner emails had been deleted, some were missing — and he waited for months before telling Congress or the court, in this case.

"He's delayed and denied the truth about this scandal for months … so I don't understand why he's still IRS commissioner.

"Forget about impeachment," Fitton told Hayworth and Khan. "They should just not fund his position, maybe, or just do other things that Congress has the power to do to make it clear he should no longer be there."

The disclosure this week that former IRS supervisor Lois Lerner used a private email account for agency business proves that "the cover-up continues" between the agency and the Justice Department, Judicial Watch President Tom Fitton told Newsmax TV on Friday.